Abstract 3417: Nanocage delivered engineered destabilized HER2 3UTR ARE reduced growth of primary EGFR T790M HER2 overexpressing osimertinib and trastuzumab resistant non small cell lung cancer and inhibited liver and lung metastasis <i>in vivo</i>
Authors: Chidiebere U. Awah, Joo Sun Mun, Baris Boylu, Alooka Paragodaarachchi, Chika Ochu, Junfei Zhang, Hiroshi Matsui, Olorunseun O. Ogunwobi
Journal: Cancer Research (2023)

Abstract Non-small cell lung cancer (NSCLC) caused more deaths in 2017 than breast cancer, prostate cancer and brain cancers combined. This is primarily due to its metastatic abilities to organs such brain, liver, bones, and adrenal glands leading to death of the patient. And there are no clinically approved drugs that can target metastasis. NSCLC with EGFR T790M overexpressing HER2 shows resistance to osimertinib and trastuzumab starting 10-18 months after therapy. For these patients, prospects are grim. To address the challenge of HER2+ drug resistant NSCLC, we have developed an innovative approach based on genome engineering of the 3’ untranslated region (3’UTR) of the HER2 gene to destabilize and degrade HER2 transcript, protein expression, HER2 dependent kinases and interactome. We report the development of two very effective HER2 destabilizing constructs which when transfected into cells lead to the specific loss of HER2 transcript, protein, downstream kinases, and loss of cell viability. In vivo, we administered the constructs complexed with a nanocage to mice bearing NSCLC. We achieved very significant control of primary tumors p=0.0001 and inhibited liver and lung metastasis and prevented hepatomegaly in mice bearing tumors that received our engineered constructs. Mechanistically, the destabilized mRNA creates premature termination codon which triggers the upregulation of nonsense mediated decay proteins UPF3B and then there is subsequent uncapping of the mRNA and the exonucleases XRN1 and CNOT1 degrades the transcript specifically and the proteins are not made available. The exogenous destabilized constructs are continuously transcriptionally active dominant negative which outcompetes the native endogenous HER2 and co-opts its mRNA for degradation. The loss of HER2 leads to loss of WNK1 and YES1 leading to activation of caspase 3,9 mediated cell death. The migration and invasion of the tumor is impaired. The constructs safely integrated into non-coding regions of the genome and caused no genome rearrangements, and we found no blood, renal, liver or electrolytes toxicities in the animals that received them. Taken together, we have developed a novel therapeutic agent that inhibits the growth of primary NSCLC and metastasis to the liver and lung. Citation Format: Chidiebere U. Awah, Joo Sun Mun, Baris Boylu, Alooka Paragodaarachchi, Chika Ochu, Junfei Zhang, Hiroshi Matsui, Olorunseun O. Ogunwobi. Nanocage delivered engineered destabilized HER2 3UTR ARE reduced growth of primary EGFR T790M HER2 overexpressing osimertinib and trastuzumab resistant non small cell lung cancer and inhibited liver and lung metastasis in vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3417.